May Garden Tips
Cornell Cooperative Extension
Needle-leafed evergreens (pines) may be pruned back (cut 1/2 of the new candle growth). For more information, see our fact sheet on this topic.
Stake floppy perennials and secure peonies.
Harden off transplants that were started indoors. Bring houseplants outside for a summer vacation after May 20. Fertilize them and keep them in the shade or they will sunburn. For more information, see our fact sheet on this topic.
Sow seeds of late herbaceous biennials and perennials.
Fertilize early annuals and vegetables. Plants outdoors grow more rapidly than they do indoors, and they may need more fertilizer. For more information, see our fact sheet on this topic. Lawns may also be fertilized now.
Weed and then summer mulch your beds and borders. For more information, see our fact sheet on this topic.
Empty the soil in your planters and replace the mix for this year's annuals.
Sow vegetable crops directly into the garden now. For more information, see our fact sheet on this topic.
Prune and divide early flowering perennials after they bloom.
Your roses need tending. For information regarding rose pruning, see our fact sheet on this topic. For information regarding rose problems, see our fact sheet on this topic.
Prune out the brown or grayish tips of juniper branches during dry weather.
Avoid applying pesticides to herbs that will be used in cooking.